hiii,
One of the heroes has been captured by the bad guys. His friends know where he's being kept, but the dungeon lies deep within the villain's impenetrable fortress, surrounded by guards, and a good old-fashioned prison break simply won't do.
However, it just so happens that one of the opposition has been spotted wandering around outside Camp Good Guy, and was conveniently dumb enough to get caught. Now there are two captives, one in each camp.
So what do the two opposing sides do in this situation? Each has something the other wants, and neither is willing to let up unless they can find a way to use the situation to their advantage. So they agree to trade hostages. They meet up at a certain location where the exchange will take place, both prisoners get to go free, and everyone's happy. Right?